Mechanism of Nicotine N-demethylation to Nornicotine in Tobacco

Nornicotine is produced by the N-demethylation of nicotine during the post-harvest treatment of tobacco leaves. Nornicotine in tobacco serves as the precursor in synthesis of the well-characterized carcinogen N'-nitrosonornicotine (NNN), one of the tobacco-specific nitrosamines (TSNAs), and consequently damages the health of tobacco smokers and passive smokers. Studies of the mechanism of nicotine N-demethylation have, over the last decades, attracted serious attention because of its importance in plant physiological research and commerce. In this review, we discuss the history and mechanisms of nicotine N-demethylation and the factors that affect this enzymatic reaction. The current advances in nicotine N-demethylation in tobacco provide important insights into improving the quality of tobacco and developing hazard-reduced tobacco products.